A carbon nanotube (CNT) is a material which is obtained by forming graphene as a two-dimensional nano material made of carbon atoms into a tube shape. As in the graphene, the CNT has excellent physical properties such as high current density resistance, ballistic conduction, high thermal conductivity, or high mechanical strength and thus is regarded as a promising interconnection material of a semiconductor device. Particularly, since the CNT is a material having a greatly high aspect ratio in which a length is 1 μm or more and 1 cm or less with respect to a diameter of 1 nm or more and 10 nm or less, it is suited for an interconnection (via interconnection) of a semiconductor device in a vertical direction. In order to form the via interconnection using the CNT, it is easiest to cause a growth of the CNT from a bottom part of a via. It is essential to use metal particulates as a catalyst so as to cause the growth of high-quality CNT. Accordingly, when a manufacturer wants to selectively grow the CNT from the bottom part of the via, it is easiest to form the catalyst metal particulates only on the bottom part of the via. Specifically, an extremely thin catalyst metal film (1 nm or more and 3 nm or less) maybe deposited before a via forming process. In some cases, however, such a thin film will adversely affect a device operation or others depending on a device. Further, there is also a method of forming a thin catalyst metal film only on the bottom of the via, but it is necessary to make misalignment of the patterning very small.
The method of depositing the thin catalyst metal film after the formation of the via can solve these problems and does not depend on a device structure, thereby having high practicality. Due to characteristics of thin film deposition technique, however, the thin catalyst metal film is deposited on the entire surface (bottom of the via, sidewalls and outermost surface of the via), resulting in causing the growth of the CNT from the entire surface. The CNT growing from the sidewalls of the via prevents the CNT growth from the bottom of the via, thus making a critical problem in that a function as a via interconnection is damaged. In addition, the CNT growing from the outermost surface makes it difficult to perform a CMP (Chemical Mechanical Polishing) process which is a post-process.